Stent for bifurcation, a system for intravascular implantation of the stent for bifurcation and a method of implantation of the stent for bifurcation

ABSTRACT

A stent for bifurcation, including two cylindrical parts: a distal part ( 1.1 ) of smaller diameter and a proximal part ( 1.2 ) of greater diameter, connected by two arranged as opposite longitudinal connectors ( 1.3 ) having length (L 1 ) of 0.5 to 8 mm and forming a cell of the stent having an enlarged surface area ( 1.4 ), the connectors having a curvilinear shape, in particular a sinusoidal shape. A method of introducing the stent and a system for intravascular implantation are disclosed.

The present application is a divisional under 37 C.F.R. §1.53(b) of, andclaims priority to, prior U.S. patent application Ser. No. 13/558,740,filed Jul. 26, 2012, which claims priority to Polish Patent ApplicationNo. P.399580, filed Jun. 19, 2012 by Emil Plowiecki and Leszek Hurkalaentitled STENT FOR BIFURCATION, A SYSTEM FOR INTRAVASCULAR IMPLANTATIONOF THE STENT FOR BIFURCATION AND A METHOD OF IMPLANTATION OF THE STENTFOR BIFURCATION, the entire content of the applications is incorporatedby reference.

BACKGROUND OF THE INVENTION

1. Technical Field

Object of the invention is a stent for bifurcation, a system forintravascular implantation of the stent for bifurcation and a method ofimplantation of the stent for bifurcation.

2. Related Art

The state-of-the art systems for intravascular implantation of stent forbifurcation, utilizing various structural solutions at implantation ofthe stent, often bring about injuries, especially at ramifications ofarteries. The most frequent problems at implantation of the stent forbifurcation include partial or complete closure of a lateral branch ofarteries, contraction of lateral branch of artery, dissection atbifurcation of vessels, a decrease in a cross section of a lateralbranch of artery as a result of covering of lumen with struts of animplanted stent, and occurrence of thrombosis foci.

To avoid such situations, at present either one stent per each branch isimplanted while using separate systems for intravascular implantationfor each of the implanted stents or one forked stent, mounted on thecomplicated system, is implanted.

Operations of intravascular implantation of stents for bifurcation usingstate-of-the-art methods are extremely complicated to implement andburdened with very high probability of various post-operationalcomplications in arteries with stents. They must be carried out insurgeries provided with very modern equipment. Furthermore, operatorscarrying out the implantation are required to have high skills and muchexperience.

Accordingly, there is a demand for new, more effective structuralsolutions for stents for bifurcation and systems for intravascularimplantation of such stents, in order to facilitate implantation at abifurcation site even by less experienced operators and to providehigher safety and efficacy of operation.

Aim of the present invention, is to increase efficacy and to facilitateimplantation procedure, thus increasing safety of operation andpromoting more wide use of stents and developing more universalconstruction of stent extendable on a balloon, which allows itsimplantation in vessels having different shapes and sizes and ofdifferent mutual arrangement of a branch with respect to the mainvessel.

From international application WO0174273A1 a self-extending stent madeof materials, such as e.g., nickel and titanium alloys, consisting oftwo segments—proximal and distal is known, one of them having greaterdiameter, and the segments being connected by at least one longitudinalconnector. That connector (or several connectors located close to eachother) is rectilinear and is located only at one side of the stent, sothat at the other side between two segments of the stent a free space isformed. The connector of the stent upon implanting in blood vesseladheres to an internal wall of the vessel and it bends in such a waythat segments of the stent change their mutual position (there is anangle between them), and free space between them is freely increased.

SUMMARY OF THE INVENTION

A stent for bifurcation of the invention, consists of two cylindricalparts: a distal part of smaller diameter and a proximal part of greaterdiameter, connected by two—arranged as opposite—longitudinal connectorshaving length of 0.5 to 8 mm, that form a cell of the stent having anenlarged surface area, the connectors having a curvilinear shape, inparticular a sinusoidal shape.

Preferably, a ratio of the distal part diameter to the proximal partdiameter of the stent is within the limits of 1.0:1.1 to 1.0:2.0.

A system for intravascular implantation of the stent for bifurcation,consisting of the proximal part and the distal part including anexternal tube, an internal tube, and a profiled balloon, according tothe invention, is characterized in that—in the distal part of thesystem—on the internal tube marked with three rings, visible at X-rays,there is a profiled balloon fastened with the proximal part to theexternal surface of the external tube and with the distal part—to theexternal surface of the internal tube, and on the profiled balloon, astent for bifurcation defined in claim 1, as presented above, is clampedin a detachable way, the profiled balloon consisting of threenon-separable parts a distal part, of smaller diameter, a proximal part,of greater diameter, and a medial part having length of 0.5 to 8 mmlocated between the distal part and the proximal part, position of themedial ring coinciding with the proximal edge of the distal part of thestent clamped on the balloon.

Preferably, a ratio of the distal part diameter to the proximal partdiameter of the profiled balloon is within the limits of 1.0: 1.1 to1.0: 2.0.

Between the long edges of the distal part of the profiled balloon andthe edge of the medial part of the profiled balloon there is an angle θthat lies within the limits of 15° to 65°.

Upon clamping the stent for bifurcation on the profiled balloon in aseparable way, a cell having an enlarged surface area of the stent forbifurcation, coincides with the medial part of the profiled balloon.

Method of introducing and positioning the stent for bifurcation by meansof an intravascular system including the stent of the invention, ischaracterized in that a guide wire is introduced to a main branch of avessel at bifurcation site, after which, a system defined in claim 3, aspresented above, is introduced into the bifurcation site, including thestent defined in claim 1, as presented above, a medial ring visible atX-rays signaling a position of the proximal edge of the distal part ofthe stent clamped on the balloon being precisely positioned at a site,where there is a groin of the vessel, such that the distal part of thestent is situated behind a fork of the artery, in a main branch, whereasthe proximal part of the stent is situated before the fork of theartery, and the medial part of the stent, with a cell of the stenthaving special, enlarged surface area, is located in the lumen of thelateral branch of the vessel, and then liquid under pressure from 6 to20 atm is introduced to the balloon, the stent is implanted, then, thefluid is removed from the balloon and the system and the guide wire arewithdrawn. On the internal tube of the system for intravascularimplantation of the stent for bifurcation, three rings visible atX-rays, are fastened, in such a way, that a first ring coincides with abeginning of long edges of the proximal part of the profiled balloon, asecond ring coincides with a beginning of long edges of the distal partof the profiled balloon, whereas a third ring coincides with an endingof long edges of the distal part of the profiled balloon.

The stent for bifurcation is suitably clamped in a detachable way on theprofiled balloon.

BRIEF DESCRIPTION OF THE DRAWINGS

The stent for bifurcation and the system for its implantation in anembodiment example is shown on a drawing, in which FIG. 1 shows a viewof the stent for bifurcation with a visible cell of the stent havingenlarged surface area, in FIG. 2 the balloon constituting an element ofthe system for stent implantation is shown, in FIG. 3—a view of thedistal part of the system for intravascular implantation of the stentfor bifurcation and its location in a branch of artery, being a site ofimplantation of the stent is shown, in FIG. 4 the stent located in thevessel at its bifurcation site upon withdrawal of the system, and inFIGS. 5A, 5B, 5C—as a matter of example—positions of the distal part andthe proximal of the stent upon its positioning in the vessel are shown.

DESCRIPTION OF PREFERRED EMBODIMENTS

A special, profiled structure of the stent for bifurcation allows suchpositioning of the system for intravascular implantation of the stentfor bifurcation during implantation of the stent for bifurcation thatthe distal part of the stent is positioned behind the fork of thevessel, in a more narrow part of the vessel, the proximal part of thestent for bifurcation is positioned before the fork of the vessel, andthe medial part of the stent, with connectors of the stent, forming atthe same time the cell of the stent having special, enlarged surfacearea, being positioned precisely in a lumen of the lateral branch,thereby preventing from blocking blood flow through the lateral branchof the artery.

Two opposite connectors assure that both parts of the stent are kept ata suitable distance from each other, but at the same time the connectorsallow, within a defined range, free adjusting to an anatomical shape ofvessels. Both parts of the stent upon implantation are supported in anuniform way by the two connectors located symmetrically on two sides ofthe stent.

Connectors are located longitudinally with respect to the stent and arecurved e.g. have a sinusoidal shape, a wavy shape, a shape of letter “S”or a double “S” shape or an accordion shape or are slightly twisted,like an extended fragment of a helix. Such shapes of connectors causethat—depending on a structure of the vessel, where the stent will beimplanted—they may be easily expanded or clamped, so that a primarydistance between the proximal part and the distal part of the stent willbe increased or decreased. A distance between the parts of the stentupon its implanting at the side of the first connector and at the sideof the second connector may be different, as it is shown in FIGS. 5B and5C. In that case, the parts of the stent are positioned to each other insuch a way that there is an angle between them. The connectors also makeit possible to carry out a slight shift of the proximal part and thedistal part of the stent with respect to the longitudinal axis of thestent. Primarily both parts of the stent are arranged in such a way thattheir symmetry axes overlap, as it is shown in FIG. 1. No matter howparts of the stent will be arranged with respect to each other uponimplanting, the two opposite connectors limit freedom of movement of thestent at its implantation and do not enable unrestricted movement of thedistal part and the proximal part of the stent.

Location of a system of three rings (markers) well visible at X-rays onthe internal tube provides precise positioning and visibility of thestent for bifurcation during its implantation in vessels. The stent forbifurcation is tightened in a separable way on the profiled balloon insuch a way that a cell having an enlarged surface area of the stent forbifurcation coincides with the medial part of the profiled balloon.Marker 7 coincides with the proximal edge of the distal part of thestent clamped on the balloon, and during implantation of the stent,marker 7 must coincide in the vessel with a beginning of the groin ofthe vessel (carina). A specific shape of the profiled balloon preventsfrom shifting the groin of the vessel (carina) during implantation ofthe stent for bifurcation, thus preventing from blocking blood flowthrough the lateral branch of the artery.

The stent expandable on the balloon of the invention is entirely made oftypical, known materials used for such purposes, preferably of stainlesssteel 316L or alloy L605.

The stent for bifurcation 1 of the invention, consists of twocylindrical segments—of the distal part, of smaller diameter 1.1 and ofthe proximal part, of greater diameter 1.2, connected by two connectors1.3 having length L1, forming the cell of the stent having an enlargedsurface area 1.4. The distal part of the stent may be longer or shorterthan the proximal part of the stent. Both parts of the stent may also beapproximately equal to each other. Prior to implantation both parts ofthe stent are positioned coaxially. The connectors, with which the stentis equipped, are arranged as opposite—i.e. on a circumference of thestent they are located 180° apart. A distance between the proximal partand the distal part of the stent may have length from 0.5 to 8 mm, e.g.from 0.5 to 3 mm or from 2 to 4 mm, or from 3 to 8 mm. Preferably bothconnectors have equal length. Preferably connectors are not rectilinearbut are of a curved shape, e.g. a sinusoidal shape.

The system for intravascular implantation of the stent for bifurcationof the invention in its distal part consists of the profiled balloon 2fastened to the system in that way that the proximal part 2.2 of theprofiled balloon 2 is fastened to the external surface of the externaltube 4 of the system, and the distal part 2.1 of the profiled balloon 2is fastened to the external surface of the internal tube 5 of thesystem. The profiled balloon 2 consists of three non-separable parts:the distal part, of smaller diameter 2.1, the proximal part, of greaterdiameter 2.2, and the medial part 2.3 of a defined length, locatedbetween the distal part 2.1 and the proximal part 2.2. The distal partof the balloon may be longer or shorter than the proximal part of theballoon. Both parts of the balloon may also be approximately equal. Themedial part of the balloon is adjusted to a distance between the distalpart and the proximal part of the stent and may have length from 0.5 to8 mm, for example from 0.5 to 3 mm or from 2 to 4 mm, or from 3 to 8 mm.

Between long edges of the distal part 2.1 and an edge of the medial part2.3 of the profiled balloon 2 there is an angle Θ. The stent forbifurcation 1 is clamped in a separable way on the profiled balloon 2 insuch a way that the cell of the stent having an enlarged surface area1.4 of the stent for bifurcation 1 coincides with the medial part 2.3 ofthe profiled balloon 2, the distal part of the stent 1.1 is mounted onthe distal part of the balloon 2.1 and the proximal part of the stent1.2 is mounted on the proximal part of the balloon 2.2.

On the internal tube 5 of the system for intravascular implantation ofthe stent for bifurcation at least one ring 7 is fastened, preferablythree rings 6, 7, 8, visible at X-rays, in such a way, that the ring 6coincides with a beginning of long edges of the proximal part 2.2 of theprofiled balloon 2, the ring 7 coincides with a beginning of long edgesof the distal part 2.1 of the profiled balloon 2, and the ring 8coincides with an ending of long edges of the distal part 2.1 of theprofiled balloon 2. The stent is tightened in a separable way on theballoon of the system in such a way that the ring 6 coincides with theproximal edge of the stent 1, the ring 8 coincides with the distal edgeof the stent 1, and the ring 7 coincides with the proximal edge of thedistal part 1.1 of the stent, in other words the ring 7 coincides withthat edge of the distal part of the stent, which is situated at the sideof the cell of the stent having an enlarged surface area 1.4.

The system for intravascular implantation of the stent of the inventionis introduced into body in that way, that the guide wire P2 is deliveredto the bifurcation site that is positioned in the main branch of theartery.

Then, the system for intravascular implantation of a stent of theinvention is introduced on the guide wire P2.

The internal tube 5 of the system for intravascular implantation of thestent is put onto the guide wire P2.

Then, while shifting the entire system for intravascular implantation ofthe stent on the guide wire P2, controlling at the same time position ofthe three rings 6, 7, 8 by X-rays, the stent for bifurcation 1 with theprofiled balloon 2 is very precisely positioned at the bifurcation site:the system is introduced on the guide wire P2 into the main branch ofthe artery, so that the ring 7 would be at the same height, where thegroin of the vessel (carina) is situated. By means of control ofposition of the marker 7 it is possible to position proximal edges ofthe distal part of the stent 1 precisely in one line with the groin ofthe vessel (carina).

Such introduction of the system for intravascular implantation of thestent for bifurcation results in that the distal part 1.1 of the stentfor bifurcation is situated behind the fork of the artery, in the mainbranch, the proximal part 1.2 of the stent for bifurcation is situatedbefore the fork of the artery, and the medial part of the stent, withthe cell of the stent having a special, enlarged surface area 1.4, ispositioned in a lumen of the lateral branch.

Then, a fluid under pressure of 6 to 20 atm is introduced to theprofiled balloon 2, which causes expanding of the profiled balloon 2,thus opening the stent for bifurcation 1. The open stent for bifurcation1 widens lumen of the vessel, thus eliminating contraction.

Upon total opening of the stent for bifurcation 1, its medial part, withthe cell of the stent having a special, enlarged surface area 1.4, ispositioned precisely in a lumen of the lateral branch, which allows freeblood flow through the lateral branch of the artery.

Then, the fluid is removed from the profiled balloon 2, the whole systemwith the empty profiled balloon 2 is withdrawn from blood circulationsystem. At the end, the guide wire P2 is withdrawn. The open stent forbifurcation 1 remains at the site, where there was contraction of theartery, thus causing its permanent widening.

What is claimed is:
 1. A system for intravascular implantation of thestent for bifurcation, comprising the proximal part and the distal partincluding an external tube, an internal tube and a profiled balloon,wherein in the distal part of the system, on the internal tube markedwith three rings, visible at X-rays, there is the profiled balloonfastened with the proximal part to the external surface of the externaltube and with the distal part to the external surface of the internaltube, and the stent for bifurcation comprising two cylindrical parts:the distal part of smaller diameter and the proximal part of greaterdiameter, connected by two longitudinal connectors arranged as oppositehaving length of 0.5 to 8 mm and forming a cell of the stent having anenlarged surface area, the connectors having a curvilinear shape, isclamped on the profiled balloon in a detachable way, the profiledballoon comprising three non-separable parts, the distal part, ofsmaller diameter, the proximal part, of greater diameter, and the medialpart having length from 0.5 to 8 mm, located between the distal part andthe proximal part, a position of the ring coinciding with the proximaledge of the distal part of the stent clamped on the balloon.
 2. A systemof claim 1, wherein a ratio of the distal part diameter to the proximalpart diameter of the profiled balloon is within the limits of 1.0: 1.1to 1.0: 2.0.
 3. A system of claim 1, wherein between long edges of thedistal part of the profiled balloon and an edge of the medial part ofthe profiled balloon there is an angle θ that lies within the limits of15° to 65°.
 4. A system of claim 1, wherein upon clamping the stent forbifurcation in a separable way on the profiled balloon, the cell havingan enlarged surface area of the stent for bifurcation, coincides withthe medial part of the profiled balloon.
 5. A method of introducing andpositioning a stent for bifurcation by means of the intravascularimplantation system according to claim 1 including the stent, whereinthe guide wire is introduced to the main branch of the vessel at abifurcation site, upon which at bifurcation site, the system includingthe stent comprising two cylindrical parts: a distal part of smallerdiameter and a proximal part of greater diameter, connected by twolongitudinal connectors arranged opposite each other and having lengthof 0.5 to 8 mm and forming a cell of the stent having an enlargedsurface area, the connectors having a curvilinear shape, is introduced,the ring visible at X-rays signaling the position of edges of theproximal distal part of the stent clamped on the balloon beingpositioned precisely at a site, where a groin of the vessel is situated,so that the distal part of the stent is situated behind a fork of theartery, in the main branch, the proximal part of the stent is situatedbefore the fork of an artery, and the medial part of the stent, with thecell of the stent having a special, enlarged surface area, beingpositioned in a lumen of the lateral branch of the vessel, and then whenfluid under pressure of 6 to 20 atm is introduced to the balloon, thestent is implanted, the fluid is removed from the balloon and the systemand the guide wire are withdrawn.